DNA with Different Local Torsional States Affects RecA‐Mediated Recombination Progression

DNA topology is thought to affect DNA enzyme activity. The helical structure of duplex DNA dictates the change of topological states during strand separation when DNA is constrained. During the repair of DNA double‐stranded breaks, the RecA nucleoprotein filament invades DNA and carries out consecut...

Full description

Saved in:
Bibliographic Details
Published in:Chemphyschem 2017-03, Vol.18 (6), p.584-590
Main Authors: Lu, Chih‐Hao, Li, Hung‐Wen
Format: Article
Language:English
Subjects:
Deoxyribonucleic acid
DNA
DNA - chemistry
DNA topology
Rec A Recombinases - metabolism
RecA-mediated strand exchange
Recombination, Genetic
single-molecule microscopy
tethered particle motion
torsional strain
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:DNA topology is thought to affect DNA enzyme activity. The helical structure of duplex DNA dictates the change of topological states during strand separation when DNA is constrained. During the repair of DNA double‐stranded breaks, the RecA nucleoprotein filament invades DNA and carries out consecutive strand exchange reactions coupled with duplex DNA strand separation. It has been suggested that torsional strain could be generated and its accumulation could inhibit strand exchange. We used hairpin and nicked DNA substrates to test how torsional strain alters the RecA‐mediated strand exchange efficiency. Single‐molecule tethered particle motion (TPM) experiments showed that torsionally constrained hairpin DNA substrates returned nearly no successful strand exchange events catalyzed by RecA. Surprisingly, the strand exchange efficiencies increase in the presence of DNA nicks or loop disruption. The dwell time of transient RecA events in hairpin is shorter compared to those found in nicked or fork DNA substrates, which suggests a limited strand exchange progression in hairpin substrates. Our observation shows that RecA generates local torsional strain during strand exchange, and the inability to dissipate this torsional strain inhibits homologous recombination progression. DNA topological states are thus important regulation measures of DNA recombination. Single‐molecule tethered particle motion shows that RecA generates local torsional strain during strand exchange and inhibits homologous recombination progression. DNA topological states are important regulatory measures of DNA recombination.
ISSN:1439-4235
1439-7641
DOI:10.1002/cphc.201601281